I am asking as a newbie who has not started assembling the CNC yet. Has anyone tried to replace steppers with nema23 ? If yes, what would be the most painless route to do that?
I have many spare nema 23 steppers and don’t want to spend extra money for 17s.
Nema 17s are not expensive. Changing things to fit nema 23s is going to cost you more, and the right sized motors are nema17.
Some people have done it on earlier versions. But I don’t think they got any appreciable benefits. And the extra lumpy mass was not good.
The modern nema17 motors are very strong. They are the right fit.
@jeffeb3 I have access to a local milling store and milled both xz and yz plates. yz plates are 10 mm aluminum and it weighs more than I thought. I have concerns about the speed of the machine running though.
This is really not a concern. The motors don‘t care about the weight. There is an old video of the LowRider 2 weightlifting. 
That could be true, but the steppers must still overcome overall inertia.
I love seeing custom builds on this forum. There are a few Lowrider 2 builds that were adapted to Nema 23 motors. If you search this forum for “Nema 23,” you will find them. I have not seen a Lowrider 3 build using Nema 23 motors.
I would expect a notable amount of redesign and expense would be associated with making the change. For example, you would likely need to move to external stepper drivers. Even the cheap external drivers like the TB6600 will cost you nearly what you would pay for Nema 17 motors. Maybe you have a source for those as well.
Also, having followed this forum for several years, the “intuition” about what changes make how much difference is often wrong. We’ve seen builds using larger (1.5KW) water cooled spindles running just fine on Nema 17 motors. Given these kinds of builds, I wouldn’t expect your heavier plates to make much difference.
If you want to do a Nema 23 build, tackle it with the love of the engineering challenge, and not with an expectation you are solving a known problem. And if you do make the build, please post your build and your experience on the forum.
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That is an excellent way to put it.
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More true for something like a 3D printer where the mass of the moving parts is most of the force.
Even with a heavy gantry, that isn’t the focus of the forces that the motors have to overcome here. We are more concerned with the cutting force on the tool. Overall speed is slow, and a lower acceleration is acceptable. Your metal YZ plates are still only a fraction of rhe weight of some of the spindles that people are successfully using on this design, like a 1.5kW Spindle
If the NEMA 23 motors are a “must have” then I’d probably suggest that there are many designs out there that center on those motors. The cnczone forums have several capable designs using those motors, though not so much in the 3D printed category.
The biggest speed limitations of V1 machines are generally not the motor strength, but the rigidity of the overall machine. The NEMA17 motors are fully capable of making the machine flex in a bad way.
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I have external drives and linear motion components from my old 6040. Transitioning from conventional machines to V1 machines makes me slightly intimidated about the performance. Even though this would be hard to ignore, I am positively biased toward the “cost/perfomance” idea behind the LR3 and open to challenges. I would be more couraged if someone had already upgraded LR3 with Nema 23
I think the LR3 maybe be the most convenient design to date for a nema23, so I’m sure it won’t be long until we see one (maybe even it will be yours). I know at least one person messing with the parts thinking about the best way to make them fit.
But since you’re in the cost/performance mindset and simply nervous about the performance, rest easy. The LR3 is very capable for a printed machine, and unless you redesign the whole thing with 23s in mind, you’re going to be disappointed. Maybe you’ll be able to cut deeper, but you’re going to be trading speed or accuracy as you add back finishing passes anyway, or just accept that the flex is going to give you off-spec dimensions. If you’re just trying to use up parts you have and are willing to accept roughly nema 17 performance by not running your 23s any harder than you would run 17s, well, that’s still better than some of the questionable things I’ve done to save a few bucks.
In terms of weight, you’re really only going to have to change the accelerations, and even then it’s impossible to know if you will need a lot or just a little. I still believe most people aren’t pushing their cncs very hard, although I’m seeing me and more. A stepper pulling 5 pounds at 100 inches per minute isn’t much different than pulling 10 pounds at 100 inches per minute. Going from 0 to 100, though, very different depending on weight.
Either way, unless you have ALL the parts you already need, you’re likely to be cheaper or at least very close to just building with the 17s, so you may as well do it and see how you like the thing. If you decide you really want larger steppers, you’ll have a cnc that can help you make the next cnc.
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This is an example of where common intuition goes wrong. Nema 23 is a downgrade, not an upgrade.
The overall machine is ‘balanced’ where the belt stiffness for example is not overbuilt, nor is it under-built in consideration of the rest of the machine. Ball screws would be stiffer but would do nothing for the other sources of deflection, and would provide effectively zero benefit in the end.
Nema 23 motors can support higher loads without skipping steps. But the accuracy becomes poor due to deflection before the Nema 17 motors skip steps. Torque is not the limiting factor so you will see no benefit without redesigning the entire machine. If you accidentally crash the machine, a Nema 17 motor will skip steps and it is pretty harmless. With a Nema 23 motor, maybe you break something (or maybe it’s fine, I don’t know).
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I never thought about that. BTW, I could not find 23.5, 25, or 25.4 mm steel tubes anywhere in Turkey. 26.9 mm is the closest diameter that locals sell. This might be a common problem for many people.
Bummer. The 26.9mm won’t come close to working.
The 25mm size is the most common outside of North America. 23.5 EMT (conduit, pipes for wires) is common in NA. 25.4 tubing is common in NA, but not at hardware stores. It is structural tubing and used by welders and mechanics.
I would try to find a metal supplier (not a home center or hardware store) and ask for 25mm outside diameter “tubing”. IDK much about Turkey, but that seems to be good advice outside of North America.
Tubing is measured by outside diameter and material thickness. Piping and conduit are measured by inside diameter (because you care what they can carry).
Please don’t be offended if you already knew all of that. I never know what you don’t know.
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I know how tubes are sized. No tube/pipe difference here. All is measured by OD. I spent the whole day trying to find the tubes. I went to the biggest manufacturers in my area but couldn’t find any size between 21 mm and 26.9 mm. Some stores suggested to go and check out hydraulic manufacturers for custom sizes. I guess, I’m supposed to give up the project.
Can you import some tubing?
I would really like to help you, but if it isn’t a good fit, then it isn’t a good fit.
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I found 23.5 mm OD EMT with 1.25 mm wall thickness. Is it OK for the default build size?
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I think that’s the standard size for 3/4" conduit, right?
That will be great for a primo at the default size. I’m glad you found something!
Yes. I ordered 6 meters of EMT. I am an electrical engineer, and motion-centric mechanical stuff blows my mind. Tolerances, metric/imperial conversion, backlashes, deflections, etc. To much trouble for such a short life.
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